The present invention relates to a novel methine dye compound, more specifically, the present invention relates to a connection-type methine dye compound where two chromophores are connected and also relates to a silver halide photographic light-sensitive material containing the compound.
Methine compounds have been conventionally used as a spectral sensitizing dye for silver halide photographic light-sensitive materials. With respect to the technology for improving the light absorptivity of silver halide grain, the following techniques are known. In order to improve the light absorptivity per one grain, the adsorption density of the sensitizing dye to a silver halide grain must be increased, however, a normal spectral sensitizing dye adsorbs to a monomolecular layer almost in the highest density filling state and does not adsorb any more.
For the purpose of solving this problem, several proposals have been heretofore made. P. B. Gilman, Jr. et al., Photographic Science and Engineering, Vol. 20, No. 3, page 97 (1976) describes a technique of allowing a cationic dye to adsorb to the first layer and an anionic dye to adsorb to the second layer using electrostatic force. U.S. Pat. No. 3,622,316 (G. B. Bird et al.) describes a technique of allowing a plurality of dyes to adsorb to a silver halide grain to form multiple layers and attaining the sensitization by virtue of Forster type excited energy transfer.
JP-A-63-138341 (the term xe2x80x9cJP-Axe2x80x9d as used herein means an xe2x80x9cunexamined published Japanese patent applicationxe2x80x9d) and JP-A-64-84244 (both Sugimoto et al.) describe a technique of performing the spectral sensitization using the energy transfer from a light-emitting dye.
These techniques have been proposed with an attempt to allow a dye to adsorb to a silver halide grain in excess of the saturated adsorption amount, however, the effect of elevating the sensitivity is not so high and there is a problem such as increase in the intrinsic desensitization.
On the other hand, U.S. Pat. Nos. 2,393,351, 2,425,772, 2,518,732, 2,521,944 and 2,592,196 and European Patent 565,083 describe a 2 components-connected dye in which two or more non-conjugated dye chromophores are connected through a covalent bond. This technique is, however, not intended to improve the light absorptivity. As for the technique of aggressively improving the light absorptivity, U.S. Pat. Nos. 3,622,317 and 3,976,493 (both G. B. Bird et al.) describe a connection-type sensitizing dye molecule having a plurality of cyanine chromophores, which is adsorbed to a grain to increase the light absorptivity with an attempt to attain sensitization by the energy transfer, where, however, remarkable elevation of the sensitivity is not obtained.
JP-A-64-91134 (Ukai et al.) proposes a technique of connecting a substantially non-adsorptive dye containing at least two sulfo or carboxy groups to at least one spectral sensitizing dye capable of adsorbing onto silver halide.
Also, in the spectral sensitization, JP-A-6-27578 (Vishwakarma et al.) uses a 2 components-connected dye in which a cyanine dye adsorptive to silver halide and an oxonol not adsorptive to silver halide are connected, or European Patent 887700A1 (Parton et al.) uses a 2 components-connected dye in which an adsorptive cyanine dye and a nonadsorptive merocyanine dye or the like are connected using a specific linking group. In these techniques, however, the sensitivity is not sufficiently elevated by the energy transfer.
Furthermore, JP-A-6-57235 (Vishwakarma et al.) discloses a production method of a 2 components-connected dye in which a cyanine dye and a merocyanine dye are connected, however, there is no Example revealing that high elevation of the sensitivity is attained by the use of this dye as a sensitizing dye for silver halide photographic light-sensitive materials.
As such, sufficiently high elevation of the sensitivity is not yet achieved in any of these patents or publications and more development of techniques is being demanded.
Accordingly, one object of the present invention is to provide a novel methine-connected dye.
Another object of the present invention is to provide a high-sensitivity silver halide photographic light-sensitive material comprising the dye.
These objects of the present invention can be attained by the following means.
(1) A silver halide photographic light-sensitive material comprising a support having thereon at least one light-sensitive silver halide emulsion layer, wherein the emulsion layer contains a compound represented by the following formula (1):
xe2x80x83Dye1"Parenopenst"L1"Parenopenst"Dye2)m1)m2xe2x80x83xe2x80x83(1)
wherein Dye1 represents a cyanine chromophore, Dye2 represents a merocyanine dye having in the acid nucleus thereof at least one dissociative group having a pKa of 5 or less, and L1 represents a linking group, m1 represents an integer of 1 to 5, and m2 represents an integer of 1 to 5.
(2) The silver halide photographic light-sensitive material as described in (1), wherein in the compound represented by formula (1), Dye1 is a cyanine chromophore, a merocyanine dye or an oxonol chromophore.
(3) The silver halide photographic light-sensitive material as described in (1) or (2), wherein in the compound represented by formula (1), Dye1 is a cyanine chromophore.
(4) The silver halide photographic light-sensitive material as described in any one of (1) to (3), wherein in the compound represented by formula (1), L1 is represented by -G1-(A1-G2-)t1-(wherein G1 and G2 each independently represents an alkylene, alkenylene or arylene group which may be substituted, A1 represents, irrespective of the direction, xe2x80x94Oxe2x80x94, xe2x80x94Sxe2x80x94, xe2x80x94SO2xe2x80x94, xe2x80x94NR3xe2x80x94, xe2x80x94COOxe2x80x94, xe2x80x94CONR4xe2x80x94 or xe2x80x94SO2NR5xe2x80x94 (wherein R3 to R5 each independently represents a hydrogen atom, an alkyl group, an alkenyl group, an aryl group or a heterocyclic group) and t1 represents an integer of 1 to 10).
(5) The silver halide photographic light-sensitive material as described in (1) to (4), wherein in the compound represented by formula (1), the linking group L1 is connected to the acidic nucleus of the merocyanine dye Dye2.
(6) The silver halide photographic light-sensitive material as described in any one of (1) to (5), wherein the compound represented by formula (1) is represented by the following formula (2): 
wherein G1, G2, A1 and t1 have the same meanings as defined in (4); X1, X2 and X11 each independently represents xe2x80x94Oxe2x80x94, xe2x80x94Sxe2x80x94, xe2x80x94NR6 or xe2x80x94CR7R8xe2x80x94; R6 to R8 each independently represents a hydrogen atom, an alkyl group, an alkenyl group, an aryl group or a heterocyclic group; R1, R2 and R21 each independently represents a hydrogen atom, an alkyl group, an alkenyl group, an aryl group or a heterocyclic group; M1 to M3, M21 and M22 each independently represents a methine group; n1 and n21 each independently represents an integer of 0 to 3; V1, V2 and V21 each represents a substituent; n2, n3 and n22 each represents an integer of 0 to 4, provided that when n2, n3 and n22 each is 2 or more, the substituents V1, the substituents V2 or the substituents V21 may be the same or different or may be combined with each other to form a ring; CI represents an ion for neutralizing the electric charge; y represents a number necessary for neutralizing the electric charge; the ring formed by Q is represented by the following formula (3-1), (3-2), (3-3) or (3-4): 
wherein R22 and R29 each independently represents a hydrogen atom, an alkyl group, an alkenyl group, an aryl group or a heterocyclic group, R25 to R27 each independently represents a hydrogen atom, an alkyl group, an alkenyl group, an aryl group, a heterocyclic group or R9-L11-, R28 represents a substituent, a hydrogen atom or R9-L11-(wherein R9 represents a dissociative group having a pKa of 5 or less, and L11 represents a linking group), provided that either one of R25 and R26 is R9-L11- and either one of R27 and R28 is R9-L11-, and X22 and X24 each independently represents an oxygen atom or a sulfur atom; and
G1 is connected to Dye1 through R1 or V1 and G2 is connected to Dye2 through R21, R22, R25, R26, R27, R28, R29 or V21.
(7) The silver halide photographic light-sensitive material as described in (5) or (6), wherein in the compound represented by formula (1) or (2), G1 and G2 each is an alkylene group.
(8) The silver halide photographic light-sensitive material as described in any one of (5) to (7), wherein in the compound represented by formula (1) or (2), A1 is xe2x80x94Oxe2x80x94, xe2x80x94SO2xe2x80x94, xe2x80x94COOxe2x80x94 or xe2x80x94CONR4xe2x80x94.
(9) The silver halide photographic light-sensitive material as described in any one of (6) to (8), wherein in the compound represented by formula (2), X1 and X2 each is xe2x80x94Oxe2x80x94 or xe2x80x94Sxe2x80x94.
(10) The silver halide photographic light-sensitive material as described in any one of (6) to (9), wherein in the compound represented by formula (2), n1 is 0 or 1.
(11) The silver halide photographic light-sensitive material as described in any one of (6) to (10), wherein in the compound represented by formula (2), n21 is 0, 1 or 2.
(12) The silver halide photographic light-sensitive material as described in any one of (6) to (11), wherein in the compound represented by formula (2), n1 is 0, X1 and X2 each is xe2x80x94Sxe2x80x94, and n21 is 1.
(13) The silver halide photographic light-sensitive material as described in any one of (6) to (11), wherein in the compound represented by formula (2), n1 is 1, X1 and X2 each is xe2x80x94Oxe2x80x94, and n21 is 2.
(14) The silver halide photographic light-sensitive material as described in any one of (6) to (13), wherein in the compound represented by formula (2), X21 is xe2x80x94Oxe2x80x94.
(15) The silver halide photographic light-sensitive material as described in any one of (1) to (14), wherein the dissociative group in the compound represented by formula (1) or R9 in the compound represented by formula (2) is xe2x80x94SO3M, xe2x80x94OSO3M2, xe2x80x94PO3M2, xe2x80x94OPO3M2 or xe2x80x94COOM, and M is proton or cation.
(16) The silver halide photographic light-sensitive material as described in (15), wherein the dissociative group in the compound represented by formula (1) or R9 in the compound represented by formula (2) is xe2x80x94SO3M.
(17) The silver halide photographic light-sensitive material as described in any one of (6) to (16), wherein in the compound represented by formula (2), L11 is an alkylene group which may be substituted or a phenylene group which may be substituted.
(18) The silver halide photographic light-sensitive material as described in (17), wherein in the compound represented by formula (2), L11 is an ethylene group.
(19) The silver halide photographic light-sensitive material as described in (17), wherein in the compound represented by formula (2), L11 is a phenylene group which may be substituted.
(20) The silver halide photographic light-sensitive material as described in (17), wherein in the compound represented by formula (2), L11 is a 1,2-phenylene group which may be substituted.
(21) The silver halide photographic light-sensitive material as described in any one of (6) to (20), wherein in the compound represented by formula (2), G1 is connected with R1 and G2 is connected with R22, R25, R26, R27, R28 or R29.
(22) The silver halide photographic light-sensitive material as described in any one of (6) to (21), wherein in the compound represented by formula (2), Q is represented by formula (3-1).
(23) The silver halide photographic light-sensitive material as described in (22), wherein in the compound represented by formula (2), Q is represented by formula (3-1) and X22 is an oxygen atom.
(24) The silver halide photographic light-sensitive material as described in any one of (1) to (23), wherein in the compound represented by formula (1) or (2), the adsorption strength to silver halide grain is Dye1 greater than Dye2.
(25) The silver halide photographic light-sensitive material as described in any one of (1) to (24), wherein the compound represented by formula (1) or (2) adsorbs to a silver halide grain through Dye1 and when Dye2 not adsorbed to a silver halide grain is excited by light, electron transfer or energy transfer to Dye1 takes place.
(26) The silver halide photographic light-sensitive material as described in any one of (1) to (25), wherein the compound represented by formula (1) or (2) adsorbs to a silver halide grain through Dye1 and forms a J-aggregate.
(27) The silver halide photographic light-sensitive material as described in any one of (1) to (26), wherein the silver halide photographic emulsion containing the compound represented by formula (1) or (2) is an emulsion in which tabular grains having an aspect ratio of 2 or more are present in a proportion of 50% (by area) or more of all silver halide grains in the emulsion.
(28) The silver halide photographic light-sensitive material as described in any one of (1) to (27), wherein the silver halide photographic emulsion containing the compound represented by formula (1) or (2) is subjected to selenium sensitization.
(29) A dye represented by formula (2) described in (6) or (15).
(30) The dye represented by formula (2) as described in (29), wherein L11 is a 1,2-phenylene group which may be substituted.